Detering or escaping factors for chickens in my experience has little to do with size. Being able to respond appropriately to predators is more important. They gotta be able to react quickly. When challenged by domestic dog or wild canids (coyote, red fox and grey fox), flying into tree or onto building is best bet. Many breeds lack needed flying ability. Flying more than once from tree to tree may be needed if tree climbing grey fox involved. Coopers and occassional red-tailed hawks have also taken my birds during day. Chickens with access to cover can evade Coopers hawk most of time. Red-tailed hawks have only taken my brids when they are isolated from flock.
Great horned owls and barred owls seem to need to have chickens on growd before attacking. We observed latter to land on branch next to chickens and then push the chicken slowly out to end of branch where the chicken would fly to ground where owl would then attack it. Chickens roosting in cedar trees or barn were less susceptable to such owls.
I have observed rosster attack hawks on ground that captured chick or hen on ground but failed to fly off immmediately. Most of my chickens have been games so a slow reacting hawk put itself at risk.
We occasionally set various ornamental / domestic breed eggs under game hens and allowed games hens to raise such chicks as their own. Despite good mothering / training, such chicks were always taken first by predators even when surviving into adulthood.
Great horned owls and barred owls seem to need to have chickens on growd before attacking. We observed latter to land on branch next to chickens and then push the chicken slowly out to end of branch where the chicken would fly to ground where owl would then attack it. Chickens roosting in cedar trees or barn were less susceptable to such owls.
I have observed rosster attack hawks on ground that captured chick or hen on ground but failed to fly off immmediately. Most of my chickens have been games so a slow reacting hawk put itself at risk.
We occasionally set various ornamental / domestic breed eggs under game hens and allowed games hens to raise such chicks as their own. Despite good mothering / training, such chicks were always taken first by predators even when surviving into adulthood.